The long term objective of this research is the elucidation of the mechanisms which are responsible for the development of sperm fertilizing capacity in the mammalian epididymis. As spermatozoa pass through the epididymis, they are sequentially exposed to varying epididymal environments created by the secretion and absorption of epididymal cells. The working hypothesis is that the maturation of the sequential plasma membrane necessary for sperm- egg interaction is dependent upon the sequential interaction with hormonally controlled epididymal secretory proteins. The following procedures have been developed: 1) maintenance in vitro of epididymal explants where the interaction between all the cells of a region and their 3-dimensional structural relationship are preserved, and 2) isolation and culture of viable epithelial and peritubular epididymal cells. The specific objectives of this proposal are 1) to study protein and glycoprotein synthesis and secretion by epididymal cells. This will be studied, after incorporation of labeled sugar and amino acids, by SDS-PAGE electrophoresis and immunoprecipitation; 2) to study the hormonal control of protein and glycoprotein synthesis and secretion; 3) to determine the binding of secreted proteins and glycoprotein to epididymal spermatozoa and their effect first on sperm-egg binding and then on sperm fertilizing ability; 4) to determine the regional differences in epididymal secretion and secretion-sperm interactions: 5) to study the epididymal secretion of glycosidases which can modify the sperm surface; 6) to study glycosidase inhibitor-induced changes in structure and function of secreted epididymal and sperm glycoproteins; 7) to study epididymal secretion and secretion-sperm interaction in mice bearing single gene mutations with normal sperm production, sperm morphology, sperm motility, and low fertility. Rabbits, rats, and mice will be used. These studies should provide important insights into the problem of male fertility.